As populations age neurodegenerative disorders, such as Alzheimer's disease, become more prevalent. Alzheimer's disease is a common form of dementia, and is progressive and irreversible. The pathogenesis of the disease is thought to involve cerebral deposits of aggregated amyloid β-peptide. The first (and rate-limiting) step in the generation of amyloid β-peptide is cleavage of amyloid precursor protein by β-secretase (β-site amyloid precursor protein cleaving enzyme-1, β-secretase-1, hereinafter “BACE-1”). This makes BACE-1 an attractive target for new Alzheimer's therapies.
Heparan sulfate (HS) and its highly sulfated analogue heparin have been shown to inhibit BACE-1 activity. HS and heparin are both glycosaminoglycans comprising 1,4-linked disaccharide units of β-D-iduronic acid or α-L-iduronic acid with N-acetyl-α-D-glucosamine (dominant in the case of HS) or N-sulfo-α-D-glucosamine (dominant in the case of heparin) and additional O-sulfate ester substituents. Heparin is a well-known pharmaceutical with anti-coagulant activity. However, the anti-coagulant properties of heparin need to be attenuated if it is to be used for other pharmaceutical applications otherwise possible side effects, such as internal bleeding and impaired blood clotting, can be problematic.
There is a need for further oligosaccharides which are inhibitors of BACE-1. Furthermore, if such oligosaccharides were synthetic, in other words, if they could be synthesised de novo, they would, advantageously, be well-characterised single chemical entities. This would make them attractive for use as pharmaceuticals. However, long linear heparan sulfate mimics can be complex and expensive to synthesise. Dendrimer constructs would provide the multiple binding epitopes required for tight binding, and are easier to prepare synthetically.
It is therefore an object of the present invention to provide compounds that are inhibitors of BACE-1, or to at least provide a useful choice.